The Bristol Taurus was offered as a fighter engine in 1939.
Main thing is to throw the cylinders and heads out and start over. There were a couple of prototype engines used the Gloster twin that disappeared after the crash and never came back again. The Service engines had a lot of trouble overheating and if the engines are overheating at 3000ft trying to make good power (1200hp?) at 15,000ft and up is going to be very, very difficult in the thinner air.
Makes one wonder why Bristol bothered. More government money I suppose. Is a jump from Perseus to Hercules unrealistic?
There were sound reasons for sleeve valves when the projects began. However further developments in fuels and poppet valve materials made deep inroads into the differences in the meantime but, when Bristol settled on the sleeve valves, they had still not eradicated the benefits that sleeve valves were to bring. Bristol manufacturing was committed to the sleeve valve in materials, machinery and tooling. By the end of the war the Hercules had become a sound 2,000bhp engine with long servicing intervals and reliability and went on being used in post war civilian aeroplanes and in licence production abroad. I agree that, with our hindsight, something along the lines of a double Pegasus would have been a better choice but, at the point of decision, it would not have been able to make the power that the Hercules eventually made even if we look at Alfa Romeo's try at a double Pegasus. The sleeve valve at that time promised to get past the inherent limitations found in period poppet valve engines. I note that the Hercules suceeded in the civilian market post war whilst the Rolls Royce Merlin did not. I also note that the last Rolls Royce Eagle 24 cylinder of 1944 was also sleeve valved.
They needed a British competitor for radial engines. Unfortunately Armstrong-Siddeley wasn't up to the task. The failed 1,000hp, 39L Alvis Pelides looks interesting. Having a monopoly on the type may have help to lead Bristol down harebrained paths. All they had to do in the early 1930s was buy a P&W engine, tear it down and exclaim, "Dammit Roy (Fedden), your sleeve valve nonsense is now off the table."
At Bristol, the sleeve valve pain and suffering was in the thirties. Did the sleeve valves cause problems for Bristol during the war? As already noted, the Taurus was too small to be a good WWII fighter engine. The Hercules had way more possibilities.
Unnecessary complexity in design, production and maintenance over the otherwise near-universally fielded ohv cannot have helped. It's the opportunity cost that we'll never know.
There were problems in 1939 and early 1940 (?).
Possibilities were untaped for much of 1940-41. They were trying and things got a lot better with the Mk VI. Hercules engine marks jump around a bit.
Different timelines. The Centaurus was basically put on hold during 1940 and 1941 while Bristol kept working at a slow pace and used some of the things they were learning with the Hercules they were able to come up a more serviceable engine before committing to combat/squadron service. Sabre was committed to combat before it was really ready, in part due the failure of Vulture.
This went nowhere. It also would have depended very much on the supply of machine tools from America. Since the US was trying to expand it's aircraft engine manufacturing by about a factor 3 every year from 1939 on supplying a major factory in Canada might not have gone well. As mentioned above, the Centaurus was not really a production ready engine in 1940. Perhaps it could have been in late 1941 or 1942 when a new factory could have actually produced engines. How many months from breaking ground on a factory to making engines at over 10 a month?
I have Bill Gunston's book Development of Piston Aero Engines here. In it, he points out that all of the important engines of WWII were running prior to the war. It takes five years or more to develop and manufacture a working engine, even if your technology is conventional. Some very good aircraft were designed over a few months. Blind, screaming panic did not work with engines.
